Knob



J. H. CLARK Jan. 3, 1939.

' KNOB Filed March 25; 1957 Patented Jan. 3, 1939 UNITED STATES PATENT OFFICE KNOB Application March 25, 1937, Serial No. 132,896

7 Claims.

This invention relates to knobs or members adapted to be'frictionally mounted on shafts, and more particularly to knobs or members having frictional means adapted to restrain axial displacement thereof and separate means for transmitting torque therebetween.

Many different methods have been proposed in the past for mounting and securing members on shafts such for example as knobs on the control shafts of radio equipment. Broadly speaking, these knobs may be allocated to one of two classes; namely, those which are secured by means of one or more set screws and those which are frictionally secured by means of a spring element in the knob. Now the accepted standard form of control shaft has a flattened outer end which is arranged to be engaged by set screws of knobs of the first class or by the spring element in knobs of the second class. Of the latter the spring element usually assumes one of two forms. Either it is a spiral spring having its end arranged to engage the flat portion of the shaft or it is a bowed spring arranged to be distorted by the flattened end of the shaft.

As long as relatively small torques were being transmitted between the knob and the control shaft, knobs of either of the above classes were more or less satisfactory. With the advent of band switches and the like in modern radio receivers it has become necessary to transmit relatively large torques between the knob and the control shaft on that portion of the equipment. Knobs of either of the above groups have not proved entirely satisfactory where it is necessary to transmit a relatively large torque. As will be apparent, knobs of the set screw type require a greater number of set screws as the torque increases and in consequence thereof the manufacturing cost of the equipment is greatly increased. Knobs of the spiral spring type are extremely objectionable since the torque is transmitted through the spiral spring and thus causes the spring either to wind up or unwind depending upon the direction of rotation of the knob with respect to the spiral. Knobs of the bowed spring type have been found objectionable in that they are frequently broken due to the high torques which are transmitted therethrough, and even in those cases where the spring does not break, the spring often snaps out of the knob.

It is an object of the present invention to provide a member having novel means thereon for securing the member to a shaft which overcomes the above-mentioned difficulties.

th iect h s nvention. is to. provide a novel knob or member which is economical to manufacture, and which is rugged and reliable in use.

A further object of this invention is to provide a member having novel means thereon adapted to mount and secure it to a control shaft including means adapted to transmit torque between the member and the shaft and additional means for resiliently restraining axial displacement of the member on the shaft. 10

Another and further object of this invention is to provide a control knob for control shafts which is formed in a novel manner and which is secured to the shaft by a novel method and means.

Another and still further object of this invention is to provide a novel composite control knob.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization, manner of construction, and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing in which:

Figure 1 is a front elevational view of a control knob illustrating one embodiment of the present invention;

Figure 2 is a rear elevational view partly in cross section of the control knob of Figure 1 taken along the line IIII of Figure 3;

Fig. 3 is a side View partly in cross section taken along the line III-III of Figure 2;

Figure 4 is a rear elevational view of the control knob of Figure 1;

Figure 5 is a side view similar to Figure 3 illustrating a different embodiment of this invention; and

Figure 6 is a rear elevational view similar to Figure 4 showing a still further embodiment of this invention.

Referring now to Figures 1 to 4 wherein the preferred embodiment of the invention is illustrated, a composite control knob I8 having a metallic core I I and a plastic exterior l2 is shown mounted onthe flattened end l lof acontrol shaft I3. Although knob I8 is particularly suitable for use on radio equipment wherein shaft I3 is connected to a portion of the equipment which is desired to be rotated, it is to be understood that the novel method and means of detachably securingknob Iii to control shaft I3. is applicable.

to.v many other forms. of. equipment wherein a 55,

member is adapted to be detachably secured to a shaft for transmission of torque therebetween.

As will now be explained, core II has one portion thereof in cooperation with the flattened end M of control shaft |3 which is adapted to transmit all torsional forces beween knob l0 and control shaft I3, while a second portion is arranged to receive a resilient member which frictionally engages the control shaft to restrain axial displacement of the knob Iii with respect to shaft I3. In order to provide a suitable means for transmitting torque between knob l0 and shaft 3, a D-shape well l5 having a circular wall l6 and a fiat wall I! is provided in the central part of the core ll. D-shape well is adapted to receive the flattened end M of control shaft l3 and make a snug engagement therewith. It will thus readily be apparent that any torque transmitted between knob l0 and control shaft I3 is transmitted through well 5 and flattened end l4.

Core H is recessed as at i8 adjacent the outer end of well I5. The particular cross-sectional configuration of recessed portion l8 may be seen best in Figure 4 of the drawing. Disposed centrally across recessed portion within suitable slots I9 and 20 is a flat spring 2|. Spring 2| may be conveniently retained within slots l9 and 20 by peening the outer edge of the slots as is indicated at 22 and 23 in Figure 4. Spring 2| is disposed substantially in the plane of the flat edge H of well 5. It will thus be observed that spring 2| frictionally engages a portion of the flattened end M of control shaft i3 exteriorly of well I5. Spring 2| is so disposed that preferably it is not distorted more than five to 15 thousandths of an inch from its normal position when the flattened end I4 of control shaft I3 is inserted in knob Ill. The distortion of spring 2| has been slightly exaggerated in the drawing for purposes of clarity of illustration. It is to be understood, however, that this distortion need only be sufficient to provide a suitable frictional engagement with the flattened end M of control shaft l3 and the distortion of spring 2| may therefore be so small that it is not visible'to the naked eye.

In order to reduce the weight of knob I0, core may be provided with quadrant recesses 24, 25, 2'6, and 21.

Although it is readily apparent that the core I! may be finished off on its outer surface and the plastic exterior l2 omitted without departing from the spirit and scope of the present invention, the preferred form is to provide core I I with a raised portion 28 which extends through the plastic exterior l2 as indicated in Figures 1 and 2. Raised portion 28 may be given any configuration or design which is pleasing to the eye and is preferably finished off with a high metal polish. The front face of knob I0 is thereby provided with a two-tone effect which greatly enhances the general appearance of the equipment with which the knob I0 is associated.

From the above description it will be apparent that I have provided an extraordinarily simple knob for control shafts which is economical to manufacture and which is rugged and reliable in use. The knob I0 may be readily assembled on control shaft l3 by moving it in an axial direction to cause the flattened end M of control shaft i3 to pass over spring2| into engagement with well l5. As the control knob is subsequently rotated it is clear that no twisting or distortibn of spring 2| results by reason of the fact that a heavy torque is being transmitted between knob l8 and secured l0 and control shaft I3 but is rather entirely transmitted through the well portion |5 of knob l0 and the cooperating portion of the flattened end M of control shaft l3. It will thus be seen that in this form of knob the objectionable features of the present known form of knobs have been overcome. To remove knob H] from control shaft l3 it is only necessary to give the knob a sufficient pull in an axial direction to overcome the frictional force of spring 2| with the flattened end M of control shaft l3.

Although the knob has been illustrated and described as being formed of a core and outer layer of some suitable material, it will be obvious that the outer surfaces of the core may be finished off in a suitable manner and the described outer layer of material omitted. Thus the core may be finished off by painting, enamelling and the like, or it may simply be given a high metal finish as is well known in the art.

It is also to be understood that although the resilient means for restraining axial displacement has been illustrated as a metallic spring which frictionally engages the control shaft, a resilient means composed of rubber or other suitable material having a configuration suitable for carrying out the teachings of the present invention may be employed with equal success.

In Figure 5 of the drawing I have illustrated a different embodiment of my invention. Those elements of this embodiment of the invention which are similar in every respect to corresponding elements in the preferred embodiment of the invention have been given the same reference numerals. The knob Hi this form of the invention is similar in most respects to the control knob of the preferred embodiment of the invention but core ll of knob I0 is provided with a slightly different shaped recess 29 as is indicated in the drawing. A substantially straight wire 30 is disposed across recess 29 in a manner similar to the way in which flat spring 2| was disposed across recess I8 and is arranged for frictional engagement with the flattened end M of control shaft l3. Although wire 30 does not provide quite as great a frictional restraining force for knob ID on shaft l3, it has been found that under some circumstances it is more convenient to manufacture a knob of this form. The manner in which the knob of this 0 form of the invention is mounted on the control shaft is the same as that previously described in connection with the preferred embodiment of the invention, it being remembered that wire I3 is not used to transmit any torque between the control knob and the control shaft.

A third embodiment of my invention is illustrated in Figure 6 of the drawing and is particularly suitable for use where it is desired toem ploy the teachings of the present invention on a wooden knob. Inasmuch as the provision of small slits such as l9 and 20 in Figure 4 of the drawing in a wooden knob would tend to cause the wooden knob to split a solid wooden knob 3| is shown as having somewhat enlarged slots 32 and 33 for the reception of the ends of flat spring 2|. Metal sleeves 34 and 35 are fitted into slots 32 and 33 to prevent direct contact of the end of spring 2| with the wood of the knob. The remaining portion of knob 3| is substantially similar to that described in connection with the preferred embodiment of the invention and includes a D-shaped well 36 into which the flattened end M of control shaft I3 is adapted to extend.

It has also been found that a knob of the form shown in Figure 6 may be formed of a plastic material. Although most plastic materials usually have a cold flow which would normally render the material unsuitable for disposing the end of the flat spring 2! therein since the ends would tend to creep, by providing recesses 32 and 33 which are lined with a cooperating sleeve 34 and 35 into which the ends of spring H are dis posed, the cold flow is not sufiicient to render the frictional engagement of spring 2| with the flattened end [4 of control shaft I3 non-effective.

Although in each of the embodiments of the invention illustrated in the drawing the spring member is shown inwardly of the shaft from the portion which engages the D-shaped well, it is obvious that this order of engagement may be reversed without departing from the spirit and scope of the present invention. It should also be noted that although the flattened end Id of control shaft I3 is shown disposed in a complementary well which is disposed intermediate the front and rear surfaces of the knob, a knob may be employed with equal success which has the D-shaped well in close proximity to one of the faces of the knobs or engage in a D-shaped slot which extends entirely through the knob.

It will also be apparent that knobs or members formed in accordance with the teachings of the present invention are extremely flexible in their application to shafts whose lengths available for mounting the knobs or members thereon vary. This is by reason of the fact that as soon as the flattened end of the shaft begins to enter the D-shaped well, the mounting is imimediately effective both in its capacity to transmit heavy torques and in its capacity to restrain further axial displacement of the knob or member with respect to the shaft. This feature is extremely advantageous from. the standpoint of manufacturing costs since a knob of a particular size may be employed on a wide variety of equipment.

While I have shown particular embodiments of my invention, it will, of course, be understood that I do not wish to be limited thereto since many modifications may be made, and I, therefore, contemplate by the appended claims to cover all such modifications that fall within the true spirit and scope of my invention.

I claim as my invention:

1. As an article of manufacture for a shaft having an end portion of D-shaped cross-sectional configuration, a member to be secured thereto having a D-shaped recess therein adapted to receive snugly a part of said D-shaped end portion, and a spring anchored in the wall of said member and arranged to frictionally engage a second part of said end portion at a point beyond the engagement of said first part with said D-shaped recess, whereby torque is transmitted through said D-shaped recess and axial displacement of said member is restrained by said spring.

2. As an article of manufacture, a knob for a shaft to be rotated having a D-shaped well therein and an enlarged outer recessed portion in proximity to the mouth of said well, and a spring member secured to said knob within said outer portion exterior of said well, said spring being disposed substantially in the plane of the flattened side of said well.

3. As an article of manufacture, a knob for a shaft to be rotated having a D-shaped well therein with an enlarged outer portion, the wall of said knob being slotted on opposite sides of said enlarged portion, and a straight spring member secured in said slotted portions, said spring being disposed substantially in the plane of the flat side of said well but exterior thereto.

4. As an article of manufacture, a composite knob for a control shaft including a metal core and a. plastic exterior, said metal core having a D-shaped well therein and an enlarged outer recessed portion in proximity to the mouth of said well, and a. spring member secured to said metal core within said outer portion exterior of said well, said spring being disposed substantially in the plane of the flattened side'of said well.

5. As an article. of manufacture, a knob having a D-shape well adapted to receive and be mounted on a complementary D-shape end portion of a shaft, a spring member secured in spaced slots on said knob exterior of said well, and arranged to engage a portion of the flat side of said shaft exterior of said well, said slots being provided with metal sleeves.

6. As an article of manufacture for a shaft having a flattened end portion, a member to be secured thereto having a recess therein complementary to said flattened end portion of said shaft arranged to receive snugly a part of said flattened end portion, and a spring anchored in the wall of said member and arranged to frictionally engage a second part of said flattened end portion at a point beyond the engagement of said first part with said recess, whereby torque is transmitted through said recess and axial displacement of said member is restrained by said spring.

7. As an article of manufacture a knob for a shaft to be rotated, said shaft having a substantially flat portion thereon and said knob having a well therein whose cross-sectional configuration is substantially complementary to the crosssectional configuration of said flat portion of said shaft and an enlarged outer recess portion in proximity to the mouth of said well, and a spring member secured to said knob within said outer portion exterior of said well, said spring being disposed substantially in the plane of that portion of said well which is complementary to the flat side of said shaft.

JESSE HOPKINS CLARK. 

